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Discussion Starter · #41 · (Edited)
I decided to play with Google Sketchup for fun...

:D

This may be a bit premature, but I put together some sketches of the amp rack and subwoofer box that I will be putting under my back seat. I still need to build some prototype boxes to explore ported vs. sealed, and to see if the PA Thin-13 and Xtant A2002 are a good combination for this build.

This shows the amp rack with the beauty panel removed:



A close-up of the amp mounting shelf, and how the beauty panel will seat. The "port" on this side represents part of a ventilation system:



This is pretty close to how it should look with the beauty panel in place:



This design will change if I decide not to go ported. Either I'll have a ventilation opening to be symmetrical with the port, or I'll hide the ventilation system if I go with a sealed box. For the construction, I plan to use baltic birch and fiberglass. For finishes, I'm still debating three main options. Option one would be paint or bed-liner, with cherry or burlwood accents. Option two would be upholstered or carpeted, with painted or bed-lined accents. Option three would be any basic 1-material finish.

I really doubt porting is feasible here, since I have so little space to work with. Still, I plan to try it in a prototype box and see how it sounds.

The sketches represent another hour of "non-work", so the project total is now 26 hours.
 

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Discussion Starter · #42 ·
Okay, morning update. I'm waiting for it to get warm enough to do peel & stick in the driver's door. :D

I put the passenger side door back together this morning, and everything fits. Nothing to see here, just stock XLT Lariat trim:



While I was at it, I decided to fine tune the time alignment. Using the stock locations, and riding with the seat all the way back, here are my path lengths:

Left speaker to left ear, 35" = 89 cm.
Right speaker to right ear, 59" = 150 cm.
PLD = 150 - 89 = 61 cm.

I set up the time alignment and speaker gains with presets so I can reverse it for left or right listening positions, and also made an "all seat" preset. Having never used time alignment in my own vehicle before, it's fun being able to flip between presets and almost feel the image moving around my dash.

That puts me another two hours in: one hour reassembling the door panel, and one hour tuning the deck. Project total is now 28 hours. Expect another update later today.
 

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Discussion Starter · #44 ·
Scooter, this post is mostly for your benefit, since I know you're planning a build in a similar vehicle.

If you decide to use the stock speaker locations (which as stated is one of the guiding principles of this build) you may have a problem with the mid-basses buzzing and rattling on low notes. The cause of this is a piece of open-celled foam inside the door card which presses on the cone of the speaker. :laugh:

I didn't want to remove the foam, because it looked like it was there to help give the door panel a snug fit. However, the buzzing (though faint) was dragging down my sound stage. When it would buzz, my attention was immediately drawn to the exact location of the speakers, but in other sections of the music the stage seemed to float higher. Obviously this is a problematic quirk, and one I could not accept in the final product.

My solution is shown in the pictures already, but I forgot to explain. By putting a speaker grille on the mids, I held the foam away, without sacrificing the snug panel fit it afforded. While the sound stage is by no means perfect, it is now coherent, and I would say very good for such poor speaker locations. :D

Anyway, that's a little tip that went a long way to improve my sound stage, if you can fit the grilles in there, do it. Otherwise you might have to cross the mids higher to avoid the buzz.

Okay, back to work! I'm about 2/3 done with the driver's door.
 

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Discussion Starter · #47 ·
First off, I deadened the driver's door. That took me about 5 hours. I didn't keep the camera rolling the whole time, because I got pretty much the same treatment as the passenger's side.



Next, I wanted to put everything back together, but ran into a little hiccup. The fabric that covers the inside of the cabin pressure equalization vents was loose, and looked too tattered to re-use:



Conveniently, I had some grille cloth left over from a pair of vintage Marantz bookshelf speakers I restored a while ago:

 

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Discussion Starter · #49 ·
I made the bond while the multiuso adhesivo (3M Super 77) was extra tacky, so I think it will hold. However, I still threw on some aluminum tape to hold it up just in case:



I would have used a charcoal grille cloth, but I'm sure no one will ever notice this:



Here's what I mean about no one ever noticing it:



The reason that vent is there is to equalize cabin pressure, that's why I didn't cover it when I sealed up the doors. I figured it's on the opposite corner from the speaker, and between the slotted metal, and plastic grille, it's just going to behave as an aperiodic vent anyway.

So fixing that grille and reinstalling the door panel took about an hour. Then I spent an hour running errands, buying fiberglass, wires, etc. I got three 12' pairs of cheap Scosche RCA interconnects. I'll run all three, even though I only plan on using one pair (for the sub) for now. It may be necessary to add a 4-channel amp in the future, who knows? Anyway, refer to my #3 guiding principle:

3) Many people say "do it once, do it right". For this build, I'll say "do it once, but leave it open-ended just in case".
It took me seven years to get the system in my Sentra to where I want it, and soon I'll be gutting the interior and re-doing the front stage. While I like the "do it right the first time" mentality for satisfying customers, I know I am personally too picky for that. My goal here is to not make it too difficult to improve the system in the future if necessary.​
As stated earlier, the project total is now 35 hours. That's all for today, I'm sure I'll be back at it within a week.
 

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Discussion Starter · #50 ·
Okay, I have a few small updates, but I'm mostly posting so I can get my brain organized and make an efficient use of time tomorrow.

I have officially decided I need a bit more headroom, so I'm going with a multi-amp setup. I have the Xtant A2002 I already posted pictures of earlier. I just ordered a matching A3001, and I need to get my hands on another A2002. So the plan is a three-amp setup. I may install two to start with, and keep fishing for a third one. Either way, I will be sure to leave room for all three.

Buying an A3001 introduces a new spin, because it only make 150 watts RMS into 4 ohms, but 300 watts RMS into 2. My subwoofer is a single 4 ohm. So basically, I need to determine if 150 watts RMS will be loud enough, or if I should buy another subwoofer and run the pair in parallel. The logistical question here is do I really have enough room under my back seat for two 13" subwoofers and three Xtant amplifiers? The odds seem slim (no pun intended), IIRC I have about 57" to work with, by maybe 15" deep and maybe 3" tall. I'll double check that tomorrow.

My plan is to build some test enclosures tomorrow , hook up my A2002 and PA Thin-13, install a ground wire, and have a listen inside the cab of my truck. If the test enclosures give me conclusive evidence on way or the other for whether a single Thin-13 can make enough bass for my tastes, I will go ahead and start getting ready for fiberglass. Expect pictures throughout the day.

One last update, I'm back up to 50 hour weeks, so I can only put in one day a week. If I go up to 60s, this build may go on hold for a month or two. Our crew is on a multi-million dollar project that is a few months behind schedule, I'm honestly surprised that I've had any free time to speak of.
 

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3 amps sounds like a good idea to me! Back in the day I did an install in a Dodge Ram where the amps were installed in the bottom of the back seat. So, once the seat was lifted with a linear you were looking at the amps behind plexi. That seat however had a tub frame which the rack was mounted to.

So, question is does your seat have frame work? If so that is free room you could use, also as thin as your amps are it would work like a champ. Also, as long as that seat is you could do your distro in it as well.
 

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Discussion Starter · #52 ·
3 amps sounds like a good idea to me! Back in the day I did an install in a Dodge Ram where the amps were installed in the bottom of the back seat. So, once the seat was lifted with a linear you were looking at the amps behind plexi. That seat however had a tub frame which the rack was mounted to.

So, question is does your seat have frame work? If so that is free room you could use, also as thin as your amps are it would work like a champ. Also, as long as that seat is you could do your distro in it as well.
No, good idea, but that won't work with this type of seat. It has a hard back made of some type of laminated metal or hard plastic, and I really don't want to cut into that. I'll post pictures later. I'm still sorting out the details of how it will all fit, I would kind of like to be able to show it off, but if I put it under the seats they will no longer fold!

I'll have to do some kind of mock-up to see what's feasible. Fortunately, I have basically the thinnest possible subwoofer for this build, with only a 2" mounting depth. I may be able to go a few inches wider than the 57" I mentioned if I make it so the seat has to be removed to mount or unmount the box. If I end up with three amps and two subs, that will really be the only option.

It wouldn't really make sense to go much wider than 60", because baltic birch comes in 5' x 5' sheets, and I would prefer to make the entire top out of on piece. I guess a little joinery never hurt anyone...
 

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Discussion Starter · #54 ·
I think you misunderstood me. the amp rack was in the seat bottom
not the back. So when you fold the seat bottom up to get under it
you were looking at the amp rack and the subs on the floor.
Naw, either way. The seat bottom and back are both the same construction. The seat bottom pivots 180° on an axis at the front of the bench, so it ends up upside down. The seat back folds forward 90°. You end up with a flat surface where you can put groceries or tools or whatever, instead of just stacking them on the seat and on the floor. It's kind of weird, but it makes a dang good cot as well. I'll miss that feature, you could seriously roll out a full sized sleeping bag and air mattress in that space. But when it folds into that position, there is even less room under the seats.
 

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Discussion Starter · #55 ·
Okay, up for the morning. I did some measuring, and I actually have 60" to work with. With all three amps installed (assuming I will find another A2002) I will have pretty close to 35" of amplifiers. There isn't enough room to stack them or overlap them, and while turning them sideways would save a few inches, it would make the wiring inconvenient.

That leaves 25" for subwoofers, basically ruling out the option of a pair of 13s. I will have to get all of my output from a single sub. The 13s are 13-1/4" wide each.

I'm now designing the test boxes, then I'll drag out the table saw and some OSB and start cutting. Pics to follow shortly.
 

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Discussion Starter · #56 · (Edited)
(Edited in 2022 to restore picture content)

Afternoon update, part one.

I spent the morning designing and modeling the test boxes. Here's what I came up with for the design:

Rectangle Font Parallel Drawing Office supplies


I determined I have about 0.5 to 0.6 CF gross to work with, and and so I worked within those parameters to come up with two options. The sealed box would be 0.46 CF net, the ported would be an absurd 0.31 CF net. As you can see here, both yield less-than-optimum response curves. I am clearly counting on cabin gain to work it's magic:

Rectangle Slope Font Line Plot


Here's a snippet from my own personal spreadsheet, I plugged in the specs just for kicks and giggles. As you can see, I am in strong disagreement with the spreadsheet about how this speaker should be used. In fact, if I went with the "optimum" box size, power handling would be shot to hell:

Rectangle Font Parallel Screenshot Number


Expect more pictures momentarily, then I'm headed to the store to buy screws and poly-fill.
 

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Discussion Starter · #57 · (Edited)
(Edited in 2022 to restore picture content)

Afternoon update, part two.

I spent a solid 40 hours caulking at work this week, I can't believe that on my day off I picked up a caulk gun to seal the inside of this box:

Wood Automotive tire Gas Grass Tire


Here's the box with the lid on. I'll cut the hole later:

Wheel Tire Wood Plant Automotive tire


Let me say this, I love working with OSB, compared to MDF or baltic birch. I always use it for prototype boxes, and back in the day (before I decided to market myself as a professional installer) I frequently used OSB for permanently installed boxes. Sure it's resonant as all get-out, and sure it needs a fair amount of bracing, but it's cheap, soft enough that I don't have to counter-sink my screw holes, and I can even sometimes get away without pre-drilling. Heck, it's even somewhat dimensionally stable! That said, it has enough drawbacks to prevent most people from touching it when it comes to car audio. At $7 to $12 per sheet, I still think it's the perfect material for prototype boxes.

Okay, now I'm off to the store to buy some supplies, I'll post progress in the evening. This two-part update represents another three hours of work, bringing the project total to 38 hours.
 

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Discussion Starter · #58 ·
Okay, I'll post evening pictures in an hour or two. Here's the gist of what I accomplished this afternoon:

1) Bought screws and poly-fill.
2) Built the ported test box.
3) Installed a ground wire.
4) Installed a temporary remote wire.
5) Installed a temporary set of RCAs.
6) Wired the Xtant A2002 (temporarily).
7) Used the subwoofer and the sealed box to set the gains by ear.
8) Enlisted the help of my wife, who is a scientist by profession, to design a double-blind experiment so I can listen to both subwoofer designs without knowing which is which. That way, I can determine which one I actually prefer without letting my ears lie to me.

Right now, I listened to one box, and am typing this while my wife installs the other subwoofer. I must say, that is seriously hot IMHO. Expect pics soon (no, not of my wife, sorry guys...)
 

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Discussion Starter · #59 · (Edited)
(Edited in 2022 to restore picture content)

Okay, evening photo updates are finally here. It's past midnight here, so I'll make this as quick as I can. That said, this is a picture-heavy update, so bear with me.

Here are the guts of the tiny ported box:

Wood Rectangle Grass Composite material Gas


By the way, do you like my rims? Here's the box with the top on:

Tire Wheel Plant Automotive tire Wood


This is a 2-gauge, solid copper terminal. I folded the 4-gauge wire in half, then crimped it with my welding crimper:

Wood Gesture Hunting knife Natural material Wrist


Heat shrink applied. I could barely fit the heat shrink over the 2-gauge terminal:

Wood Electric blue Font Magenta Fashion accessory


Here it is installed:

Tire Automotive tire Tread Synthetic rubber Gas


More pictures on their way...
 

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Discussion Starter · #60 · (Edited)
(Edited in 2022 to restore picture content)

Here's how I cut my circles. By the way, this method keeps me from needing a plunge router.

First, I cut a very shallow cut. This lets me double check the diameter before fully committing:

Wood Grinding Saw Drilling Gas



Next, I drill a hole the same size or just slightly larger than the router bit. Insert the bit and start cutting from there:

Bedrock Floor Road surface Beige Flooring



The cuts usually leave a little nub like this:

Automotive tire Tread Synthetic rubber Outdoor shoe Asphalt



The detail sander makes short work of that:

Wood Automotive tire Finger Gas Electric blue


And, voila!

Automotive tire Wood Road surface Art Automotive wheel system



Still more pics are on their way.
 
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